Many computers include at least one hard disk for data storage and a read/write head for writing data onto the hard disk or reading data from the disk. Small computers, such as personal computers, may have a hard disk and read/write head combination. Larger more powerful computers almost always are equipped with a number of these hard disks and read/write heads. There are also many data storage devices that use hard disks and read/write heads.
Generally as the computer operates the read/write heads fly over the hard disk. However, at times the read/write head contacts the disk such as during takeoff and landing of the read/write head.
An unintended contact between the head and the disk that results in a data loss is called a head crash. Head crashes result from a variety of reasons and are always undesirable in a data storage device.
Generally, data storage devices can operate for many hours before a head crash occurs. Head crashes can occur prematurely. The materials which make up the read/write head or hard disk are one possible cause for a premature head crash. The majority of the head is made from a ceramic material. The hard disk is a metal disk substrate with several thin layers of other materials which hold individual magnetic charges and lubricate the head to disk interface. If the ceramic material making up the head is too hard or brittle it can chip during takeoff or landing. If the bonding between the layers on the metal substrate is poor a layer may flake off when the head lands or takes off. In either case, the chip or flake could possibly lie on the disk and trip the read/write head on a subsequent rotation causing a head crash. One type of hard disk has a carbon overcoating. If the carbon overcoating is too soft it can accumulate on the head, eventually begin to drag and cause a premature head crash.
To date, the methods and apparatus used to test the materials making up the head and disk have been inadequate. Most test the bulk properties of a material rather than the surface properties. in addition, no tester seems to simulate the contact that occurs between the head and the disk during landing or takeoff.
As a result, there is a need for a tester capable of testing the surface properties of a material. Furthermore, there is a need for a tester and methods for using the tester that simulates the conditions that occur when the head and the disk contact during takeoff and landing.